This application is based upon European Application Serial Number 00401937.8, filed on Jul. 6, 2001, from which the benefit of priority is hereby claimed, and the full content which is incorporated herein by reference as though fully set forth.
1. Field of the Invention
The present invention relates to a method of manufacturing multiple complex planar optical devices and the resultant devices.
2. Technical Background
Optical networks used in the communications industry require many complex optical components, examples of which include Nxc3x97M switches, gain-flattening filters, variable attenuators, add-drop multiplexers, splitters, and other components. An efficient manner in which to design and manufacture such components is to use planar optical devices, or chips, inasmuch as many optical functions can be implemented on the same substrate. Presently, integrating a large number of optical functions into a planar optical device is limited by the relatively small size of a silica substrate due to fabrication techniques such as chemical vapor deposition (CVD).
In order to provide more complex optical devices, individual chips containing a number of optical functions have been mechanically joined to one another. One approach for connecting chips utiles a suitable mounting platform and optical fibers for coupling waveguides of individual chips to corresponding waveguides of an adjacent chip. The optical path adhesive employed to couple the optical fibers to the waveguides must exhibit a high degree of light transmittance to reduce propagation losses at the bond joints and must have a refractive index which closely matches that of the optical components being joined. In the past, optical adhesives, such as NOA61, available from Norland Products, Inc, New Brunswick, N.J. have been employed for coupling multiple optical function chips using optical fibers. There exists a need for joining different optical functioning devices to form complex networks in which the optical fiber interconnection between the chips and the mounting of chips to substrates, involving multiple complex steps, both of which result in relatively costly optical systems, are eliminated.
The method and resultant structure of the present invention provides for the coupling of a plurality of individual planar optical components to one another by aligning and mechanically coupling the substrates of planar chips carrying optical waveguides thereon to one another and subsequently coupling the aligned optical waveguides, such as by heat fusion. Depending upon the substrate material, the substrates can, once precisely aligned to one another to align mating waveguides utilizing an active alignment process, be coupled by bonding utilizing either heat fusion in the case of a silica substrate; or by a bonding adhesive in the case of a silicon substrate. Once the aligned substrates have been mechanically coupled to one another, the optical waveguides are coupled utilizing, for example, heat fusion and preferably a focused CO2 laser which completes the mechanical and optical interconnection of multiple devices. It is possible with such alignment and coupling by bonding and/or fusion to couple numerous chips in an array which can subsequently be packaged for use in relatively complex optical networks. The resultant devices display a high level of reliability, are relatively inexpensive to manufacture, and display excellent operating characteristics.
Additional features and advantages of the invention will be set forth in the detailed description which follows and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described in the description which follows together with the claims and appended drawings.
It is to be understood that the foregoing description is exemplary of the invention only and is intended to provide an overview for the understanding of the nature and character of the invention as it is defined by the claims. The accompanying drawings are included to provide a further understanding of the invention and are incorporated and constitute part of this specification. The drawings illustrate various features and embodiments of the invention which, together with their description serve to explain the principals and operation of the invention.